Speculators flocked to the company, listed on the AIM stock exchange, and some even joined activists outside the site, celebrating the progress of their investment by tweeting videos of oil tankers being driven away.
When the earthquakes began, opponents of the well found their numbers swelled.
“It’s a great campaign,” one activist admitted. “Nothing gets people going like an earthquake.”
Seismologists from Imperial College London, the University of Bristol and the British Geological Survey (BGS) hope to settle the debate with an academic article, due to be published later this month, that will conclude the earthquakes are natural.
The research, to be published in Seismological Research Letters, found that the relatively small amount of oil being pumped out of the well, during what is known as “flow testing”, was unlikely to have had an impact “extending more than a few hundred metres”.
What’s more, seismologists found “no correlation” between the timing of the earthquakes and these tests. The earthquakes began in April, but the flow testing did not start until July.
Additionally, they concluded that a 16-year-old oil well in Brockham, more than four miles from the epicentres, was also an unlikely cause.
Their research stemmed from a 20-person meeting in October 2018, which was organised by regulator the Oil and Gas Authority (OGA) and led by the BGS after Prof Haszeldine and others first aired concerns and called for a moratorium.
Prof Haszeldine was the only one to walk away from the meeting unconvinced that the earthquakes were natural.
He accepts that he was a lone “dissenting voice”, but said it was a case of “groupthink, versus individual thought”.
“That doesn’t mean I’m right, but all I’m saying is I don’t think my questions were answered.”
Along with two junior colleagues from the University of Edinburgh, he sent an outline of his theory to Surrey County Council in February after UKOG submitted plans to drill four new boreholes.
With only small amounts of oil being extracted at the time of the earthquakes, he looked for a cause that did not involve heavy industrial activity.
“Rather like Sherlock Holmes and the Silver Blaze, it is the absence of evidence in this case which drives us to a hypothesis,” Prof Haszeldine said.
He concluded that a build-up of gas might be released periodically to reduce pressure in the well, thus causing the earthquakes.
“That removal of pressurised gas is like letting pressure from a truck tyre – the mass of the truck collapses the tyre,” he said.
Earthquakes in Britain
The vast majority of the 20 to 30 earthquakes that are felt across the UK each year are magnitude 3 or under and do no damage.
None of the Surrey swarm makes it on to the BGS’s list of 58 “significant British earthquakes”, all of which have a magnitude of 4 or more. Less than half of the 30 or so Surrey earthquakes were reportedly felt by people.
The most powerful, on 27 February, was recorded at 3.1 magnitude and seismologists say it was felt by so many people largely because the epicentre was relatively close to the earth’s surface at 2km.
Britain’s largest earthquake – a 6.1 magnitude event at Dogger Bank in the North Sea in 1931 – was strong enough to damage properties on the east coast, despite being 60 miles offshore.
More than 1,200 buildings were damaged and three people killed in a 4.6 magnitude quake in Colchester in 1884.
In contrast, there have been 14 earthquakes worldwide with a magnitude of 6.3 or higher in 2019 alone.
UKOG chief executive Stephen Sanderson rejected Prof Haszeldine’s theory, pointing to Dr Hicks’ research, which shows the earthquakes were “1.1 to 1.4km deeper than anything that we are doing at Horse Hill”.
“The mechanism he’s suggesting is very arm-wavy. To people who don’t understand the way things happen in the subsurface, it has a veneer of credibility, but for people who do, it verges on being ludicrous.”
He called Prof Haszeldine a “well-known anti-oil and gas guy”, who was “motivated by his own political agenda”.
Dr Hicks, who shared seismological data on social media after the earthquakes, said he had faced pressure from both opponents and supporters of the well.
“You are completely stuck in the middle. They will just take a small piece of what you say and use it to fit their agenda, which is irritating.”
Fracking – the process of using high-pressure fluid to release natural gases, which has been linked to earthquakes in Lancashire – has been ruled out as the cause in Surrey, with UKOG insistent it only conducts conventional oil extraction.
However, Richard Selley, emeritus professor of earth science and engineering at Imperial College, said it was “very hard to get the message across that the one cause that can be ruled out is hydraulic fracturing”.
In a report presented at the OGA workshop in October, he wrote that 2010 anti-fracking film Gasland “casts a long shadow”, adding: “Some folk anticipate flames emerging from their water taps.”
For her part, Mrs Von Kaufmann said she was “not totally anti-oil,” but added: “I just feel the Weald is not the place for it.”
In the past year, hairline cracks have appeared in her Victorian home and she fears earthquakes will continue and increase in magnitude.
“That’s very scary,” she said.
Prof Haszeldine, who describes himself as “wearing two hats” – one of which is as the director of a research group promoting climate-change solutions – accepts that he might be “subject to unconscious bias”.
“I absolutely recognise that, but then I consciously try and make sure that I’m not going to get dragged into being a professional objector.
“I am not going to be parading up and down with a placard, saying ‘stop all oil production at Horse Hill’.”
He does, however, question the neutrality of the regulator. Established in 2015, the OGA’s founding principle is to “maximise the economic recovery from UK oil and gas”.
Prof Haszeldine said it was a “big weakness” that left the OGA “conflicted all the time because its job is to produce more oil”.
“If there is a judgement call and it’s not absolutely compelling that they have to close everything down, then their inclination will be to keep everything going.”
The OGA said its focus on “maximising economic recovery” only applied to offshore oil exploration, adding that it also “has a role in evaluating any effects of petrochemical exploration and production along with other regulators”.
After hearing of Prof Haszeldine’s theory, Reigate MP Crispin Blunt wrote to Environment Secretary Michael Gove last month calling for an independent inquiry to “investigate categorically whether or not there is a causal connection”.
Energy minister Claire Perry responded that a connection was “unlikely”, citing the opinion of the OGA and the BGS. She said that she did not believe an inquiry was “currently necessary”.
Mr Blunt said he was focused on establishing “what level earthquakes would need to reach before one starts worrying about it”.
Dr Hicks sympathises with residents looking for answers in the wake of what were “pretty shocking events to those who felt them”.
Humans naturally look for “coincidences and correlations” and have long sought meaning in the mysterious movements beneath their feet, he said.
“The Japanese used to think there was some giant catfish under the ocean that was being held down by a demigod and when that god became distracted, the catfish slammed its tail against the earth,” he said.
He said the Surrey swarm earthquakes were “probably natural events, just due to natural tectonic stresses”.
As to fears they will continue, he said: “The most likely scenario is they will just decay and die off, but then we said that back in the autumn of last year.